When an engine is about to blow, you'll get some kind of warning. When a system is straining against itself, on the verge of collapse, pushed too far, cracks will start to show.

And so it is with our planet. New afflictions arrive to dwarf the old ones, and we discover that instead of everlasting life and happiness, our technological advances seem merely to have brought us cancers, contaminants and heart disease. Transformed from elaborate ecosystems into shadowy husks our oceans and forests have been laid waste as we bravely exploit where no 'man' has exploited before. We ditch our waste into the rivers and then wonder why we have to shell out on water filters. We blow some holes in the sky and seem surprised that we need sunblock, year-round.

Some of the damage cannot be undone. The extinction of 50 different species of plants and animals a day in a tropical rainforest is pretty much irrevocable, but changes can be made now to ensure that the future is sustainable. This article is about what you can do.

A fair amount of environmental destruction can be linked to the way we pattern our lives. From car use to energy consumption there are ways of living which place more or less of a burden on this poor old planet of ours.

A vegetarian diet is well known for its health benefits. Radically lower heart disease and cancer levels have been discovered in vegetarians, and 95 per cent of food poisoning cases occur in animal foods. Studies have shown that cutting back on the meat in your diet can cut premature mortality by up to 20 per cent and that a vegetarian diet can fight osteoporosis and diabetes. The fact that a vegetarian diet may be a safer bet for our environmental future may, however, have escaped you until now.

The livestock industry is one of the biggest. In the UK alone we have 12 million cows, 44 million sheep and 7.4 million pigs. In battery cages and broiler sheds we also have several hundred million chickens and turkeys. 77 per cent of our land is used for agriculture, of which up to 85 per cent is used to produce meat. Where we don't graze livestock, we grow crops to feed to livestock. Agriculture is big business and yet this land-hungry industry contributes only 1.5 per cent of our gross domestic product.

These huge crowds of animals do more than occupy the land - they pollute it too. Manure, slurry and sewage sludge, full of the heavy metals added to feed, is spread upon the land every day. In the Netherlands they have found themselves with too much shit for too little land, and have declared the country a 'manure surplus region'. The muck they can spread gives off ammonia - a major cause of acid rain - while the remainder is shipped off and dumped on the developing world. Here in the UK things are almost as bad. The accumulation of heavy metals in the soil is reaching serious proportions, and every year between 2,000 and 4,000 serious water pollution incidents can be linked directly to industrial farming.

The unwitting farm animals pollute the air too. Muck spreading and slurry storage cause a good deal of discomfort for those caught 'down wind' from Old MacDonald's factory farm. Over 3,500 complaints are received every year about 'farm smells'.

After carbon dioxide, methane is the second most common greenhouse gas, and increasing levels of this gas in the atmosphere are worrying experts as it has 11 times the global warming capacity of carbon dioxide. Cows belch and burp and incredible 60 litres of methane every day, and when added to the flatulent excesses of other farm animals, they represent the single largest source of methane in the UK, belching and farting a massive 26 per cent of all emissions.

Meat production is a smelly, polluting business, but it doesn't end there. More land needed for more cattle means the continued destruction of otherwise valuable wildlife habitats. Though we've long since lost most of our forest here in Britain, we still have our hedgerows, yet over 52,000km of hedgerow have been lost since 1984 through agricultural expansion. Beyond our shores, an area of tropical rainforest the size of England is destroyed every year, in regions like South America the majority is cleared for cattle ranching, even though the soil is virtually useless once the forests have gone. For the four or five short years that the soil will sustain pasture, the ranchers will only manage to stock their range with one head of cattle per hectare.

The meat or fish on our plates is doing more than just damaging our land and forests. With nets large enough to capture 12 Boeing 747 jets and radar planes to track shoals of fish, huge factory trawlers are decimating the last few remaining stocks of fish. Of the world's 22 major fisheries all but two have reached their limits and 7 are in serious decline. In the North Sea we take out half of all the fish stocks every year, dragging thousands of dolphins, whales and sea birds with them.

In our rivers and estuaries, fish producers have adopted the techniques of the factory farm, and are caging tens of thousands of salmon and trout in hideously cramped conditions. Packed in together, the fish are an ideal breeding ground for disease and so pesticides and antibiotics have to be added to the water, some of which have been linked to cancer in humans.

These large, static fish populations have more than just cages in common with the factory farm. Pollution from sewage is just as worrying on fish farms, a single ton of trout can create a pollution load equivalent to the untreated sewage of 100-200 people.

There is, of course, an alternative. A vegetarian diet is not just better for you and the 900 animals you would normally eat during the course of your lifetime. Vegetarians can exist on around 30 per cent of the agricultural land used to produce meat. Feeding perfectly good crops to animals is an inefficient and short sighted way of producing protein - 10kg of vegetable protein to produce just one kg of meat! Using less land, more sensibly could mean fewer pesticides and fertilisers and more land available for wildlife. The developing world could stop shipping us valuable grain for our livestock, and wouldn't have to deal with the shit they produce.

A vegetarian diet will cut out the antibiotics, growth promoters and chemicals found in meat, and would go a long way to reducing the pollutants in our drinking water. You'll be healthier almost immediately, and you'll be making sure that your little piece of the planet stretches just that little bit further.